Testing sample biological specimens is commonly done, for example, to check for the presence of an item of interest, which item may be or include all or portions of a specific region of DNA, RNA, or fragments thereof, complements, peptides, polypeptides, enzymes, prions, proteins, messenger RNA, transfer RNA, mitochondrial RNA or DNA, antibodies, antigens, allergens, parts of biological entities such as cells, virons or the like, surface proteins, or functional equivalents of the above, etc. Specimens such as a patient's body fluids (e.g., serum, whole blood, urine, swabs, plasma, cerebral-spinal fluid, lymph fluids, tissue solids) can be analyzed using a number of different tests to provide information about a patient's health.
In such testing, it is imperative that the specimens be handled in a manner which prevents contaminants from being introduced to the specimens, whether from the outside environment or between specimens. For example, where the HIV virus from one specimen is inadvertently allowed to contaminate the specimen of a different patient, the resulting false positive test result could potentially have catastrophic psychological effect on the patient, even should subsequent testing later discover the error. Moreover, since such testing is highly sensitive, even the smallest amounts of contamination can cause erroneous test results. Simply put, it is imperative that the specimens be properly handled.
In such sophisticated testing, it is also imperative that the various reagents which may be used in the testing be properly handled as well, not only to avoid contaminants but also to ensure that the proper reagent in proper quantities is used at appropriate times.
Commonly, such testing is accomplished using automated devices which handle multiple specimens and fluids (typically, reagents). Such automated devices typically will use sets of pipettes to move various fluids between their original containers (usually receptacles such as open topped tubes) and containers in which the specimens are to be processed. For example, a set of 8 specimens may be contained in 8 tubes or other receptacles loaded in a rack on the device, and a head carrying 8 pipettes will, through programmed motion, move the pipettes into those 8 tubes, where a vacuum will be applied to extract a selected amount of each specimen from its tube into the pipettes. The head will then retract the pipettes from the tubes and move to another set of tubes located at a processing station, depositing the extracted amounts of each specimen from the pipettes into sets of testing tubes.
In such automated devices, racks or trays of multiple tubes are usually moved from one station to the next for different stages of processing. For example, a heating element may be provided at one station, and a magnetic element introducing a magnetic field in the tubes may be provided at another station. Further, in such situations, multiple trays of multiple tubes may be actively processed in series and simultaneously at different stations. However, such processing can result in resource contention, where one rack of tubes is delayed from being placed at a station while another rack of tubes completes its processing at that station when, as is commonly the case, the processing time at one station is different than the processing time at another station. For example, a tray of tubes which have completed processing at one station may be delayed from being processed at the next station until another tray of tubes at that next station has completed its processing there. Like a chain which is no stronger than its weakest link, such an automated device will provide an overall processing time which is a function of the processing time at the slowest station. Of course, a slow overall processing time can reduce the amount of tests which are performed during a given day, and thereby either delay the completion of tests or require significant additional investment of capital for additional devices to allow for a desired testing capacity level.
At the processing stations of such automated devices, the specimens are variously handled according to the purpose of the testing (e.g., incubated, prepared, lysed, eluted, etc.). For example, the specimens may be prepared for analyzing, as for example by separating DNA or RNA from the specimen. The specimens may also or alternatively be analyzed. Commonly, such processes involve the addition of various fluids (typically reagents) to the specimen in each tube. For example, in a first step, a reagent may be added to each of the tubes to wash the specimens, and second and third (and more) reagents may be added to the specimens in the course of carrying out other processes to, for example, unbind and/or separate the DNA or RNA of interest so that it may be extracted from the specimen in each tube for subsequent testing. Similar processes, in which the same or different reagents are added to and/or extracted from the tubes, may also occur after the specimen has been prepared as part of analyzing the prepared specimens.
In some processes, magnetic fields have been used to assist in separating analytes of interest from the fluid in the tubes. For example, analytes of interest have been bound to magnetic particles within a reagent and a magnetic field applied to pull the particles and bound analyte to one side of the tube, whereby the reagent may be drawn out of the tube to leave a concentration of the analyte therein. Where it has been necessary to adjust the magnetic field within the tubes (e.g., in order to change the location where the analytes are to be drawn), the tubes have been moved in order to accomplish the desired orientation of the magnetic field in the tubes.
The handling of the reagents and other fluids with automated devices such as described above can be problematic. Though the reagents may be automatically moved from receptacles to the specimen containing tubes in the processing station by use of the head and pipettes such as noted, it is in the first instance necessary to load the appropriate reagent into the appropriate receptacle on the device in order to ensure that the head and pipettes are adding the appropriate reagent to the appropriate specimen containing tube at the appropriate time in the process. Further, it should be recognized that it is necessary for the receptacles to be readily cleaned, whether to remove possible contaminants or to permit use of different fluids in connection with different processes. As a result of such requirements, the receptacles are typically readily removable from the apparatus for such action.
Heretofore, loading the appropriate reagent into the appropriate receptacle has been accomplished in several different ways. In one such procedure, the individual who is controlling the device manually measures and adds the reagents to receptacles, and then places those receptacles on the device. In another such procedure, the loading of reagents is automatically accomplished by the device itself, which uses some transfer apparatus (such as a head and pipette(s) as previously described) to move the reagents from bulk supplies of the reagents provided with the device.
Removing reagents from tubes is similarly accomplished, such as by use of a head which positions pipettes in the tube and vacuum draws the fluid from the tubes into the pipettes. Such a process can be time consuming, and tie up the head from other uses, particularly if prevention of contamination between tubes makes it necessary to use a new pipette with each tube. In such cases, it may be necessary to repetitively move the head to discharge, discard and pick up new pipettes every time fluid is drawn from tubes (e.g., a head carrying eight pipettes may have to be cycled six times when used with a tray of 48 tubes, where each cycle requires discharging and discarding used pipettes, and picking up new pipettes). Of course, in such situations, multiple pipettes will be consumed at some cost. U.S. Pat. No. 6,117,398 alternatively discloses drawing fluid from the bottom of a sample vessel, wherein a valve is situated between every sample processing vessel and the waste container.
The present invention is directed to overcoming one or more of the problems as set forth above.